Codec errors

Codec errors belong to the dialect because only the dialect knows whether a block, union variant, or response field is valid.

Encode

Encoders return typed unsupported-block or unsupported-conversation errors. Bedrock additionally exposes ToolSchemaError, ToolInputError, and EncodeError; OpenAI Responses exposes ServerDecodeError and UnsupportedBlockError; Anthropic exposes a large typed set in its own errors.go, including UnsupportedBlockError, UnsupportedEffortError, UnsupportedAudioError, UnsupportedRefusalError, UndeclaredThinkingDialectError, ThinkingBudgetError, UnsupportedConversationError, StreamEventDecodeError, and StreamAPIError. Read each dialect’s errors.go for its full set rather than treating any list here as exhaustive. Use errors.As and retain the original error chain.

body, err := anthropicapi.EncodeRequest(req, false)
if err != nil {
	var unsupported *anthropicapi.UnsupportedConversationError
	if errors.As(err, &unsupported) {
		return fmt.Errorf("remove conversation %s: %w", unsupported.Conversation, err)
	}
	return err
}
_ = body

Decode

Malformed JSON is returned by the decoder or wrapped in the dialect’s decode error. Unknown response block/item types are skipped where the package documents tolerant decoding; required structure such as an absent OpenAI choice or Bedrock output.message fails instead. A candidate-less Gemini body becomes a PromptBlockedError carrying an allowlisted block reason, safety ratings, and the charged usage when promptFeedback explains itself, and a bare failure.APIError otherwise. Provider error envelopes are converted to failure.APIError or a stream API error.

Source and proof

• openaiapi/errors.go
• openairesponses/errors.go
• anthropicapi/errors.go
• bedrockconverse/errors.go

Run go test ./codec/....